Bore hole surveying apparatus and method



' May 3, 1938. G. MALMGREN BORE HOLE SURVEYING APPARATUS AND METHOD 2Sheets-Shee't 1 Filed Dec. 21, 1954 T N m W a 5 m M 1 M 5 A 7 u 5 5 QnqvM 4% a v VIM 6 V 1 1 a "Q 7 W 7 9 ma 3 y 19335 G. MALMGREN 2,116,120

INVENTOR, GEORGE MALMGREM h": AT'I RNEys.

Patented May 3, 1938 UNlTED STATES- PATENT OFFICE BORE HOLE SURVEYINGAPPARATUS AND a LIETHOD George Malmgrcn, San Francisco, Calif.

Application December 21, 1934, Serial No. 758,621

' Claims. (01. 33-2055) ratus; to provide bore hole surveying apparatuswhich will determine the inclination and direction of inclination atvarious depths of a bore hole; to provide a bore holesurveying apparatuswhich is not affected by the earths magnetism; to provide a bore holesurveying device giving 5 a continuous record; to provide a bore holesurveying apparatus giving a polar coordinate record; and to provide abore hole surveying appa-' ratus giving a true survey of bore holeinclination.

Other objects of my invention will be apparent or will be specificallypointed out in the description forming a part of this specification, butI do not limit myself to the embodiment of the invention hereindescribed, as various forms may be adopted within the scope of theclaims.

In the drawings, Figure 1 is a longitudinal view partly in section andpartly in elevation of a preferred embodiment of the survey apparatus ofmy invention. I

30 Figure 2 is a view partly in section and partly in elevation, takenthrough the plane indicated by the lines 2-2 of Figure 1.

Figure 3 is a plan view of a chart taken as indicated by line 3-3 inFigure 1.

35 Figure 4 is a view partly in section and partly in elevation takenthrough the plane indicated by the lines 4-4 in Figure 1.

Figure 5 is a view partly in elevation and partly in section takenthrough the plane indicated 40 by the lines 5--5 in Figure 1.

All figures are diagrammatic for ease of illustration.

Referring directly to the drawings for a detailed description of thepreferred embodiment 45 of my invention, as shown, a substantialcylindrical casing I, preferably seamless, is provided with a closed endwall 2, the opposite end, which 1 in service is the upper end, beingprovided with threads 4 adaptedto receive a screw cap 5. This 50 screwcap is provided with a'cable attachment aperture 6 andalso with asealing flange I, which bears against a lead gasket 9 inserted 'inagasket groove H! in the cylinder wall. For 'shallow well' surveys I alsoprefer to perforate the cap and 55 attach thereto by means of a couplingII a seamless steel tubing I2 for purposes later to be explained.

. The interior of the cylinder is provided with an upper shelf l4 and alower shelf l5, each provided with central bearings l6, preferably coneshaped, in which are inserted inner case pivots ll. These pivots arepreferably of hardened material, and are the sole support of an innercase l9, which carries the various instruments and is freely revolvablewithin the main casing I. I prefer to mount a number of instrumentswithin the casing and while I will describe them as being in aparticular order from top to bottom, it is to be understood that thisorder is of no particular advantage and they may be arranged indifferent relative positions if it appears desirable.

Beginning, then, in the upper-part of the inner casing, I prefer tomount on an upper instrument shelf a depth correction chart table 22,upon which is mounted depth correction chart 24. The table 22 with itschart, is rotated by means of a Bourdon tube 25 connected to atorrection chart shaft 26 by an operating link 21.

The Bourdon tube is actuated by pressure changes due to temperaturechanges around and within a thermometer bulb '28 connected with theBourdon tube by a capillary tube 29. The shaft 26 will then be rotatedby an amount determined bythe temperature change to which thethermometer bulb assembly 28-29-41 is exposed. Contacting 30 the chartwith its zero position near the axis of the chart is a correction chartink syphon or stylus 30 which is adapted to be moved in a curved pathover the chart passing through the central portion of the chart by meansof an aneroid stylus arm 3| operated through an aneroid link 32 which inturn is connected to an aneroid chamber 34 of the usual type. Thus, inthe cooperation of the two movements, the arm 3| is moved outwardly andaway from the center of the depth 0 correction chart in accordance withthe varying pressure afiecting the aneroid, and the chart itself will berotated in accordance with temperature by the thermometer assembly, anda'permanenttwo dimensional record will be made on a the chart of thecombined movements. This rec- Immediately below the depth correction as-1 sembly I prefer to mount a gyroscopic compass assembly. This assemblycomprises agyroscopic ,motor 35 which is preferably a motor having awell balanced and relatively heavy armature r0 tating in a motor frame36. The motor frame is,

rotatable around the horizontal axis of the inner case, a motor casepivot 31 entering a bearing band 39 attached to a motor case bearingblock 40. The motor case is also provided with a case extension shaft 4|passing through the center of the bearing block 40, carrying on itsupper end a compass table 42 having fixed thereon a compass chart 43.Bearing block 40 also carries an insulated disc 44 upon which slip rings45 are mounted, contacted by brushes 45 attached to the motor case andconnected by leads 41 to the motor. The slip rings 45 are provided withflexible leads 49 which in turn run along the side of the inner casingl9 to the lower wall'thereof which is provided with casing slip rings 50connected to casing brushes 5|, which are energized by a battery, notshown, in a battery chamber 52 in the lower end of the main casing.

The bearing block 40 is mounted on gymbals 53 rotatable within the caseon gymbal pivots 54 fastened to the side walls of the inner case. Thegyroscopic motor, therefore, may assume an upright position within thecase irrespective of the inclination of the casing.

Mounted on the bearing block 40 by means of an angle arm 55 is ananeroid assembly 56 similar in all respects to that described foroperation in conjunction with depth correction chart 24 and having itsstylus positioned to mark the chart. The operation of the compass willbe given later in describing the overall operation of the device.

Just below the compass assembly I prefer to mount an inclinationrecorder assembly on an inclination shelf 59. This assembly comprises afairly heavy pendulum weight 50 connected to a bearing pin Si by apendulum rod 62 so that when the casing is perpendicular the pendulumwill lie in the central axis of the casing, and will be free to swing inone plane only as determined by the position of the pendulum pin 5|. Thependulum is then connected by a gear sector 64, only a part of which isshown, to an inclination chart table 65 upon which is mounted aninclination chart 66, through a gear box 61 in which I prefer in anywell known manner to step up the motion of the pendulum 36-1 in orderthat the movements of the pendulum be greatly magnified on the chart 66.The polar coordinate record on the chart 56 is made by an aneroidassembly 61 similar in all respects to the other aneroid assembliespreviously referred to with its recording stylus contacting the chart.Thus it can be seen, that all of the three charts will have upon thempolar coordinate records, and that all the records will be continuousand will have pressure asone coordinate.

In setting up the instrument for use, I prefer to hold the casing l inupright position over the bore hole to be surveyed, with the cap 5removed.

I also prefer to remove upper shelf l4 and to provide the inner casewith a removable top Hi through which entrance to the inner casing maybe had. The various units therein are removable by removing theirrespective wall screws. The units may then be raised one by one throughthe top of the case, checked, their charts removed andchanged, and theunits replaced.

It is also within the scope or knowledge of those skilled in the artthat apertures may be provided in the inner case side walls so thatcharts may be removed and replaced without withdrawing the units.

After the charts have been placed upon the tables and the units securedin their proper locations, inner casing I9 is lowered into the maincasing i until lower pivot I1 is immediately over lower bearing l6, butnot sufliciently close to cause brushes 5| to come in contact with rings50. Top plate 10 may then be screwed in place.

The next step is the orienting of the gyroscope and the pendulum. Toorient these devices I prefer to set up by transit a stake placed wellaway from the bore hole so that the segment between the stake and thebore hole axis has the bearing north zero degrees east. Any convenientform of sight may then be dropped into the sight holes 69 and the innercase rotated by sighting on the stake until pendulum 60 swings in themeridian plane. Inasmuch as the pendulum is preferably placed at thebottom of the inner case, marks denoting the plane .of the pendulumswing may be conveniently placed on the top of the inner case tofacilitate sighting.

After the inner case is properly oriented, it is necessary to orient thecompass chart. This may be done in any manner obvious to those skilledin the art but may be conveniently accomplished by inserting a tool orwire through hole 12 in top plate 10 past chart table 22 until the endof this tool contacts chart table 42. By means of this tool the motorchart table is rotated so that the tangent at the center of the chart tothe circular line having the boring north zero degrees east is also inthe meridian plane; and, for ease of sighting, chart table 42 may havethereupon an index mark adapted to cooperate with another mark on theinner casing.

After the motor table and easing have been oriented, the entire innercasing is lowered a. short distance until pivot l1 enters bearing l5,and brush 5| contacts rings 50, thus starting the motor. It ispreferable to have the chart table 42 and chart so connected to themotor that when the motor table is properly oriented the plane of thefly wheel or the 'armature of the motor now acting as a gyroscope isalso in the meridian plane. As is well known, under these circumstances,the gyroscope acts as a true geographic compass and will, providing itis properly mounted and unrestrained, remain in the meridian planethereafter. In this case, irrespective of the rotation or inclination ofeither of the casings, the motor will maintain itself with its armaturerotating in the meridian plane and thus will turn relative to the stylusand record upon the chart 43 the turning of the casing l9 together withthe depth indication as created by the aneroid assembly 55, causing theoutward movement of the stylus.

After the gyroscope, as the motor may be termed,'has been set with therotating element in the meridian plane and the inner casing set so thatthe pendulum swings in the same plane. Upper shelf I4 is then placed inthe outer casing with upper pivot l1 engaging upper bearing I 6, thusmaking casing l9 freely rotatable, the cap 5 is screwed on tightly andthe hollow seamless tubing I2 is attached to the cap. A cable is thenattached to the eyelet 6 and the entire casing I lowered into the borehole unreeling not only the cable but also the seamless tubing l2, thesurface end of which is open to the atmosphere in order that the weightof the air column, clue to the depth of the instrument may act upon theaneroids 34, 56 and 61, all of which have had their styluses set at azero point on the inner portion of the charts.

While I have described my device as equipped for shallow wellmeasurements, it is obvious that for deep well measurements cap 5 mayhave substituted therefor the lower endof a dry drill pipe string. Theuse of dry drill pipe is well known in the art, and venting of the maincasing to the outer atmosphere will take place through the bore of thedrill pipe, which may be run dry and empty to considerable depths, evenin wells filled with mud and water.

As the case descends. a continuous polar coordinate record will be madeon all three charts N, 413 and 66. Let us assume, for example, thatafter the casing has been lowered a certain amount that an inclinationof the borehole occurs. If such does happen, pendulum to swings awayfrom the vertical axis of the device, thus giving the inner casing it aheavy sidemoment which tends to and does rotate the inner case it on itspivots ll. Inclination will be recorded on chart 66 as the chart will beturned by the gears attached to the pendulum and the polar coordinatetraced. The angle of rotation of case it will be shown on chart dd,because when the case M is rotated due to the action of the pendulumcreating a heavy side and consequent rotation, the gyroscope willmaintain its position thus causing chart 43 to rotate with relation tothe operating pen or stylus contacting therewith. Should another changein inclination take place, as the casing proceeds on its downwardjourney, the inner casing id will be rotated still again. recording thechange both in inclination on the chart B6 and in azimuth angle on thechart w.

All the while the casing is being lowered, the air pressure isincreasing and the respective aneroid styluses are being moved towardthe periphery of the charts, giving. on the trace of each chart anuncorrected depth coordinate in addition to their inclination, directionof inclination, and temperature coordinates.

When the entire instrument reaches the bottom of the hole, the length.of cable reeled out is read on a suitable instrument to give .the totaldepth reading and thereafter by' correction from the depth correctionchart, the exact depth can be obtained of any intermediate point asindicated by the intermediate readings of all the aneroids.

It will thus be seen that I am able by the use of my invention to obtaina bore hole survey which is continuous from top' to bottom of, the holeand which may be corrected for any intermediate depth. The importance ofsuch a continuous record is obvious.

When any surveying instrument is lowered into a bore hole, and whichis'so constructed as to record inclination and direction intermittently,or where a single record is taken at the bottom of the hole, dataobtained from such intermittent or single records is almost invariablyentirely misleading, as the records do not tell the average angle of thehole nor do they in any way give a clue to the actual distance of thebottom of the bore hole from the perpendicular passing through the borehole opening. An exaggerated example of this would be a case where abore holesurveying instrument is lowcred-into a hole, this instrumentmaking a reading every hundred feet. If we could consider an examplewhere all the inclinations took place in the hundred feet betweenreadings and the places where the readings took place were vertical, wewould get from that crooked hole a complete record indicating aperfectly straight hole. The bottom of the hole, however, would be at a.distance away from the vertical which would be dependent upon the angleof inclination of the hole as occurring between readings. Likewise, in asimilar case, such intermittent records could be procured showing auniform angle of inclination at each reading and yet there might be agreater angle or a lesser angle-between readings so that when the entireset of intermittent readings was obtained the picture or graph drawn ofthe hole, using the readings as a plotting basis, would give anabsolutely and entirely erroneous picture of the actual inclination ofthe hole. In the device, however, which I have just described, acontinuous reading is obtained. Any minute or temporary inclinationswhich tend to throw the bottom of the hole away from or toward theperpendicular are all of record and thus by a continuous plottingstarting at the top, the actual and complete inclination of the hole canbe obtained andwhen the projected graph of the hole is made, it can beimmediately calculated therefrom what the actual distance the bottom ofthe holeis from the vertical, and theazimuth of the line con necting theprojected top of the hole with the projected bottom of the same hole,can be ascertained.

My instrument is ideally adapted for deep wells, as well as relativelyshallow ones, because depth has no influence whatever upon the recordedinclination. The increased air pressure due to depth has no noticeableeiIect on the recorded temperatures as the pressure increase could notpossibly compress the mercury with which bulb 28, capillary tube 29, andBourdon tube 25 are filled. 'The increased air pressure will cause theaneroids to record which, of course, is the purpose of the aneroids. Therecorded pressure, along with the accurate measurement of the length ofpipe or cable used to reach the desired depth, and the temperaturerecorded at that depth, is accurately translated into feet depth. Theonly inaccuracy which may be found is one which is due to the fact thatthe error of the gyroscope increases with time. However, I have foundthat in'modern well rigs, drill pipe may be made up sufiiciently rapidlyand lowering accomplished in either of the manners described .in such ashort time that this error may in most cases be entirely neglected. Itis, however, possible to check thiserror and correct for it by test runsof the instrument under known conditions.

I have been able to make in practical form a device as described whichhas been used within a five and one-half inch casing and operative.under any and all conditions so far encountered in oil wells. It shouldalso be pointed out that the device is fully operative even thoughtemperatures at relatively large depths are increased. It is true thatthe air contained within themstrument and the steel tubing l2, or in thecase of deep wells dry drill pipe, is heated, but if theinstrument werenot lowered as the temperature was raised the actual pressure within theinner casing I! would be reduced due to the fact that the specificgravity of the air column, the height of which would be constant, woulddecrease as the air expands. By lowering the instrument an air columnconstantly increasin in height is acting on the aneroids, and thisheight can be substantially and accurately determined from the pressurerecorded by the perature recorded. As pointed out above, theincreased-air pressure within casing i9.does not aneroids. and thesubstantially accurate temat all affect a Bourdon tube,filled withmercury, and will only slightly affect one filled with nitrogen at apressure of two hundred to two hundred and fifty pounds per square inch,as are commonly used in recording thermometers. The records of thelatter are accepted as substantially correct for all commercialpurposes. Therefore, a substantially correct temperature is recordedwhich for all practical purposes can be used to correct the aneroidreadings. Further, the aneroids are not used to determine the depth. Thedepth is accurately determined by measuring the cable or drill and pipeused to lower the instrument, and the aneroid readings are merely usedto conveniently interpolate the intermediate depth where changes inbearing and inclination take place.

I claim:

1. In combination, bore hole survey apparatus comprising a cylindricalouter casing capable of being lowered into a bore hole, a concentricinner casing rotatable around an axis parallel to the axis of said borehole, a compass mounted in said inner casing, a chart positioned by saidcompass, a recording stylus rotating with said inner casing andcooperating withsaid chart to record relative movement thereof, apendulum mounted on said inner casing having its suspension crossing theaxis of said cylinders and swingable in a single plane parallel to andincluding said axis, said pendulum being of sufficient weight to rotatesaid inner casing due to the shift of center of gravity thereof whensaid axis is inclined, said shift being the'sole factor causing rotationof said inner casing, thereby recording direction of inclination.

2. In combination, bore hole survey apparatus.

comrising a cylindrical outer casing vented to atmosphere, means forlowering said easing into a bore hole meanwhile maintaining said vent, aconcentric inner casing rotatable around an axis parallel to the axis ofsaid bore hole, a compass mounted in said inner casing, a chartpositioned by said compass, a recording stylus rotating with said innercasing and cooperating with said chart to record relative movementthereof, a pendulum mounted on said inner casing having its suspensioncrossing the axis of said cylinders and swingable in a single planeparallel to and including said axis, said pendulum being of sufficientweight to rotate said'inner casing due to the shift of center of gravitythereof when said axis is inclined, said shift being the sole factorcausing rotation of said inner casing, thereby recording direction ofinclination, and means for modifying the relative movement of saidcompass and said stylus by a pressure factor.

3. In combination, bore hole survey apparatus comprising a cylindricalouter casing capable of being lowered into a bore hole, a concentricinner casing rotatable around an axis parallel to the axis of said borehole, a compass mounted in said inner casing, a chart positioned by saidcompass, a recording stylus rotating with said inner casing andcooperating with said chart to record relative movement thereof, apendulum mounted on said inner casing having its suspension crossing theaxis of said cylinders and swingable in a single plane parallel to andincluding said axis, said pendulum being of sufficient weight to rotatesaid inner casing due to the shift of center of gravity thereof whensaid axis is inclined, said shift being the sole factor causing rotationof said inner casing, thereby recording direction of inclination, andadditional means for recording the degree of pendulum swing in saidplane.

4. In combination, bore hole survey apparatus comprising a cylindricalouter casing capable of being lowered into a bore hole, a concentricinner casing rotatable and balanced around an axis parallel to the axisof said bore hole, a compass mounted in said inner casing, a chartpositioned by said compass, a recording stylus rotating with said innercasing and cooperating with said chart to record relative movementthereof, a weight mounted in said inner casing and free to move acrossthe axis of said cylinder to change the center of gravity thereof,thereby causing rotation of said inner casing with respect to said chartand a record when said axis is inclined.

5. In combination, bore hole survey apparatus comprising a cylindricalouter casing capable of being lowered into a bore hole, a concentricinner casing rotatable and balanced around an axis parallel to the axisof said bore hole, a compass mounted in said inner casing, a chartpositioned by said compass, a reco'rding stylus rotating

